Sherlock Gets Dirty
by wendymarlowe
Summary: Sherlock believes profanity is the refuge of a lesser mind. John tries to prove that profanity and precision both have their place. John talking dirty can get *anyone* going, even a "married to his work" detective . . . and then Sherlock returns the favor. (He's not very good at it.)
1. Chapter 1

John's ears were still ringing when they got back to the flat. Apparently it wasn't just a turn of phrase - the nine sailors he and Sherlock had run to ground and gotten arrested that afternoon really had sworn with impressive fluency. And volume.

"Some of those combinations were new to me," he commented out loud. "Rather impressive, really - even though I was in the army and all."

Sherlock shrugged off his coat and made a disapproving sound. "Profanity is a refuge for those with lesser vocabularies. I prefer to be more precise."

"Precision and profanity aren't mutually exclusive, you know," John retorted, more out of a desire to contradict Sherlock than any particular need to argue his point. "Every term has its use." He let himself stare off into the space over the mantel, trying to remember a particular blonde he dated for a while during his years at uni. What was her name? Charlene? No, Cheryl. She had been particularly fond of precision in that aspect of her vocabulary - loquacious, even . . .

"Rubbish." Sherlock collapsed into the couch and propped his feet up on the armrest. "You're talking about during sex, I assume?"

John snorted. "Yes, Sherlock, sex. It happens when two people who love each other very much decide to make a baby - actually, did you ever get the 'where babies come from' speech? I bet it was from Mycroft."

Sherlock audibly rolled his eyes. "Don't change the subject, John. I was just saying, I don't see any way talking dirty - using profanity - could possibly be considered sexy. It's just biology, after all."

"Have you ever actually _had_ sex, Sherlock?"

"Why would I?" Sherlock steepled his fingertips and stared at the ceiling. "It's a biological drive of the body, John, not a pursuit of the mind. Boring."

John couldn't suppress his laugh. Sherlock turned his head and glared, clearly offended at John's response, but really, what else did he expect? "I'm continually amazed," John admitted, "at how phenomenally knowledgeable you are about some things and how mind-bogglingly ignorant you are about others. The mind is the greatest sex organ there is, and sometimes dirty talk is the difference between good sex and _great_ sex. The same physical stimulation but a different biological response, all based on brain chemistry."

"Rubbish," Sherlock repeated.

"Look, just because you've never had good sex -"

"Prove it," Sherlock snapped.

John blinked at him. "Prove you've never had sex?"

"No, John, prove that precise profanity has a purpose. Convince me."

"You want me to talk dirty to you."

Sherlock popped up from the couch and started pacing the floor. "Yes, if that's what it takes. I refuse to believe that mere words could have any effect on sexual arousal. Perhaps in certain situations, clinical terms are useful for negotiating further liaisons, but in neurochemical terms -"

"Fine." John watched Sherlock pace for a moment and formulated his plan of attack. This would be worth it, if only to put the damn detective in his place . . . John stalked toward Sherlock, cutting off his pacing and forcing him back toward the doorway.

"John?" There was a tiny hesitation in Sherlock's voice, and John's resolve firmed. It wasn't often that he got to show up his flatmate, but it was so nice when those occasions arose. This was going to be _fun_.

He kept pressing forward, one step at a time, until he had Sherlock pinned against the door to the flat. John was careful to not touch Sherlock, just to herd him with his body, but Sherlock seemed to understand and didn't fight the attempt. A touch of pink highlighted the detective's cheeks as John grabbed the doorframe on either side of him, boxing him in.

"You look bloody gorgeous when you blush like that," John said in a deliberately low voice, keeping his eyes on Sherlock's. "You've already got those ridiculous cheekbones, so high and sharp, and seeing them with spots of color - I can't decide whether I want to snog you or slap you."

A tiny crease between Sherlock's eyebrows appeared, a sure sign he hadn't quite deduced what was going on. "John?" he repeated with a bit less strength.

John plowed on forward. "What type of lover are you, Sherlock?" he murmured. "You like it gentle, like to be petted and caressed?" He suited his tone to his words. "Or do you like it rougher?" He lowered his voice even more. "You want me to drag exactly what I want out of you, want me to make you beg for it? You would, you know - you may say you've never begged for anything before, but I can change that." He leaned in further. _"I can make you crave me._"

Sherlock drew in a breath. "I . . ." He faltered.

And John didn't let him take the time to regroup. "I'm so hard for you right now," he lied. Well, kind of lied - John tried not to think about how much this fun little exercise in proving Sherlock wrong was actually turning him on.

The tiny change in Sherlock's posture told John he was on the right track.

"It's too bad I'm not gay," John continued in a mock-regretful tone. "Because if I were, I know exactly what I would do."

"What?" Sherlock whispered.

John let only half of his smile show on his face, turning it into a smirk. "First, I would pin you against this door, chest to chest. You think you could avoid me? You may be taller, but I've got the advantage here - I'm not the one half-dizzy with lust." He drew himself up straighter, more aggressive, lessening the height difference between them. "I'm the one who's done this before - I could make you lose your _ever-fucking mind_. You're so proud of that great brain of yours, Sherlock - how do you cope when it's turned off? When your cock is so hard it aches and then you come until you can't bloody breathe? I can leave you _gasping_, Sherlock, not even able to remember your own fucking name. All you'd be able to think of would be me. My mouth around your cock, my hands fondling your bollocks, my fingers stroking you from inside your arse. And you wouldn't be able to do a bloody thing about it, you'd be wound so tight - fuck, that's a beautiful thought. Sherlock Holmes, great detective, naked and panting and desperate for me to pound into him and fuck him into submission."

Sherlock's lips parted and he sucked in a long breath. The color in his cheeks was even more intense, two bright spots of rose against his pale skin. John pressed his advantage.

"The fucking wouldn't come first, you know," he said, voice husky. He hadn't done that intentionally . . . this must be affecting him too . . . John swallowed the sudden hesitation and leaned in even closer, his lips a mere inch from the exposed column of Sherlock's throat.

"What do you taste like, Sherlock?" he asked. I want to suck right here." He let go of the doorframe and traced a finger lightly over the flap of Sherlock's collar, not close enough to touch skin but near enough to make Sherlock shiver. "I want to suck until I leave a bruise, a mark so everyone who sees you will know what we've been doing, what you let me do. They already suspect we're shagging, of course, but how do you think it will be once they have proof? Sherlock the slag. I think I'd enjoy every minute of it, knowing they all guessed it was me fucking your brains out." John withdrew his hand and let out a puff of breath against Sherlock's throat. "Mine."

Sherlock let out a tiny moan, which went straight to between John's legs and stayed there.

"If I were gay, I'd pin your hips back to the door here and tear open your trousers with my teeth." He drew back a bit and let his eyes dip down to Sherlock's crotch, then slowly raised them again until he could see the wonderment on his flatmate's face. "I'm very good with my mouth, Sherlock. _Very good_. Have you ever had someone's mouth on you before?"

A tiny shake of Sherlock's head.

"Yeah, I thought so. I can suck your bloody brain out through your cock, Sherlock, and the only thing you'll be able to do is moan. Your legs will give out and the only thing holding you up will be my mouth on your dick and my hands on your arse. Or would you prefer _in_?" John deliberately brought one forefinger to his mouth and sucked on it, wetting it all the way to the hilt. He drew it out slowly, eyes locked with Sherlock's the entire time, and brought it down to trace feather-light over the zipper in Sherlock's trousers. "Picture me inside you, Sherlock. My fingers filling your arse, but not enough - not quite enough -"

Sherlock's eyes fluttered closed and he moaned, long and desperate. "_John -_"

But then his eyes snapped open again, full of something -

He twirled away and shouldered past John's body, but not fast enough to keep John from seeing the wet spot spreading across the front of his trousers. John dropped his forehead against the door and sighed. "Sherlock -"

"Don't."

John wanted to put a hand on his shoulder, to offer that connection, but he sensed Sherlock wouldn't welcome it. "It's nothing to be ashamed of," he said lamely.

"That doesn't happen."

"Obviously it just did."

"I haven't done that since I was fourteen."

John adjusted his own, rather noticeable erection, and retreated to the armchair. Best to be casual about this whole thing, if Sherlock was going to have a freakout. "It's only natural, Sherlock, especially if you haven't . . . indulged in a while. I came in my pants a few times when I was a teenager too."

"Not that, John," Sherlock bit out. "I haven't done that - _any_ of that - since I was fourteen. I wasn't expecting it to happen now."

John pinched the bridge of his nose. Life with Sherlock was constantly surprising, and yet . . . "You mean you haven't had an orgasm since you were a teenager?"

Sherlock growled something John interpreted as affirmative.

_Christ_. John took a moment to choose his words carefully. "Is it - do your identify as asexual?"

"I don't identify as anything, particularly."

"So - not gay?"

"Never had the inclination to find out." Sherlock gestured futilely to the spot on his trousers. "Although it looks like a possibility, wouldn't you say?"

"Do you get turned on at other times, though? Do you find particular people or situations arousing?"

Sherlock glared at him, and John reflexively threw up his hands to ward off the accusation in Sherlock's face. "Relax, I'm not trying to pry - well, I guess I am, but it's the doctor in me asking. No medical reason for this, then, just . . ."

"Just never interested," Sherlock finished for him. "Sex always seemed like it would be horribly _boring._"

"Yes, well now you know better."

Sherlock grunted.

"And you can admit I was right. About profanity and precision not being mutually exclusive." John snorted. "Come on, I at least deserve to hear you say you were wrong for once. That there's something you're not an expert about."

"One data point, John, and I'm not exactly a typical experimental subject."

"That's true - but that one data point supported my hypothesis, didn't it?"

Sherlock closed his eyes and inhaled deeply. "Yes, John. I suppose it did."


	2. Chapter 2

The next two days were awkward, but relatively quiet - John and Sherlock weren't _avoiding_ each other, exactly, but neither of them went out of their way to say much. It was only natural, John supposed - whatever-it-was that had happened between them, it was clearly something Sherlock wasn't prepared to process. Odd, to find something his oversized brain couldn't cope with in a matter of seconds.

Thus it was a complete surprise when Sherlock started a conversation one evening with an offhand, "I've been watching a lot of porn."

John choked on his own tongue so badly his eyes watered. "Pardon?"

"Porn, John." Sherlock paced toward him, until they were toe-to-toe and Sherlock was looming over where John was curled on the couch watching the telly. "I've been watching a lot of it since . . . before."

_Ah_. John's perfectly adequate intelligence made some connections. "Research?"

"Exactly." Sherlock frowned. "I was expecting your browser history to only contain porn with women in it, but you have an impressive variety."

John drew in a deep breath, held it, and exhaled slowly. "You went through my browser history. Sherlock, I _delete_ my browser history, for that very reason."

Sherlock waved John's objections away with a graceful wave of his hand. "Took me less than five minutes of digging. But it was helpful - I didn't know what I was looking for, so I appreciate you having narrowed the field down for me, as it were."

John rubbed his forehead. "Christ."

"So." Sherlock locked his hands behind the small of his back and resumed the pacing he had been doing before he started this incredibly odd conversation. "I'm definitely not straight, but I don't think I'm gay either. Actually, not a lot of what I saw did anything for me, physiologically, but I felt it best to be thorough. And of course, it's possible it was the live element - you being physically here in the room - that made the difference. Before."

"Possibly." John couldn't believe he was actually discussing this with a straight face.

"I wasn't able to test that hypothesis, unfortunately," Sherlock continued. "I attempted to convince Molly to 'talk dirty' to me yesterday, but she actually refused. First time she's refused me anything, actually, and she was altogether acting odd about it."

John's laugh bubbled out at that. Sherlock's eyebrows drew together in confusion, but John couldn't keep a straight face -

"Sorry. Sorry! Just - the thought of you propositioning Molly -" He snorted again, then forced himself into a more sober expression. "Sherlock, you can't just go around demanding people talk dirty to you. Especially someone like Molly, who has fancied you for ages."

"Why not? You didn't seem to mind."

_That's the rub, isn't it?_ John pinched the bridge of his nose and suspected the whole _I'm not gay_ thing might not be the unassailable truth he had always assumed. Trust a mad detective to drag that out of him. "It's not . . . it's not an experiment, Sherlock. Not something you can demand data for."

Sherlock blinked. "Right now I have a sample size of one. That's not data, John, that's an _anecdote_."

"Christ." John looked back up, forcing himself to look his flatmate in the face. "What did you say to her, anyway? Volunteer to drag her into a janitor's closet for a quick shag?"

Sherlock recoiled at the suggestion. "_Molly?_ No, of course not! I merely requested her assistance with an experiment, which she was quick to promise. And then I said I wanted her to describe having sexual intercourse with me, in as much detail as possible. And she sputtered and looked like she was going to cry and she ran off."

This time John managed to catch the laugh before it escaped his lips. "You're hopeless."

"High-functioning sociopath."

"Doesn't that make your one-person sample data invalid?" John realized what he had just said - or at least failed to contradict - and raced to backtrack. "Not that I think you're a sociopath, Sherlock, just . . . from an experimental standpoint -"

"No, you're right," Sherlock conceded. "I may be a sociopath, but I'm not a robot." He frowned, quick flicks of his eyes taking in John's posture as he sprawled on the sofa, probably his pulse and breathing rate and God knows what else. "I want to have sex with you," he finally announced.

John's train of thought - such as it was - derailed completely. "Sorry, what?"

"I want to have sex with you," Sherlock repeated, a hint of annoyance in his voice. "I want to place my knees on either side of your hips and sit on your lap facing you, and I want to push my tongue into your mouth. I want to cup my left hand around your cervical vertebrae to anchor your head and prevent you from accidentally pulling away, and I want to use my right hand to trace the skin over your cheekbone and your jawline. And I want to grind my pelvis into yours, so I can feel your erection against me as I do it."

"Christ, Sherlock." John knew there was more to it than that - more he should say - but the word _erection_ seemed to have short-circuited something.

And Sherlock had no intention of stopping his monologue, it seemed. "I want to use my tongue and my lips and my teeth to elicit a stronger response from you during the kiss," he continued. "I want to hear you make involuntary noises against my mouth. And I want to trace from your cheek down over your chest, skipping over that frankly hideous jumper, until I can tug the hem out from the waistband of your trousers and slip my palm inside to touch your bare skin. I want to run my hand upward underneath your shirt and your jumper, high enough I can feel the hair on your chest between my fingers. I want to trace mathematical equations across your chest with my fingertips, just to know that you can feel the contact too."

_Mathematical equations . . . what -_

"And then I want to strip off your jumper, and your shirt, and my own if you haven't done it for me already by that point. I want to have your naked chest pressed against mine, so I can feel your chest hair tickle against my nipples." He smiled a bit, taking in the stunned look John was certain must be showing on his face. "I have particularly sensitive nipples, John. You might want to know that. I didn't realize there was a range, but my research over the last few days confirms it."

"Ah . . . good to know . . ."

"Yes." Sherlock bit his lip. It was probably a practiced move, but _fuck_ it was having the intended effect on John's libido. John felt like he had been poleaxed by something entirely unexpected and - until now - invisible.

"I want to find where your nipples fall on the range of sensitivity, too," Sherlock added. "Are you within a standard deviation of the mean?"

"I -"

"I'll make sure to excite you, too." Sherlock tilted his head back, tracing one long finger slowly down the pale column of his throat, and John's mouth went dry. "You want to suck hard enough to leave a bruise on my neck? I'll tilt my head back like this so you have all the access you require. Break as many subcutaneous blood vessels as you like - leave a ring of bruises around my neck like a collar, like a pre-coital 'John was here' sign. I'll wear them proudly. Lestrade won't say anything, of course, but Donovan and Anderson surely will. They'll congratulate you."

John swallowed. Hard. "Sherlock, I wouldn't -"

Sherlock pressed on, talking over John's stumbling objections. "I _want_ your mouth on me, John. I want your mouth over my carotid and my pectorals and my nipples and my abdominal muscles and my testicles and my penis. Particularly that last one. I want you to use your mouth to turn my brain off completely, to redirect blood flow entirely to my groin. You're proud of how good you are at fellacio? I'm metaphorically aflame with anticipation to learn just how accurate your assessment of your skills is. I want you to make me moan, John, to make my vision flicker and the muscles in my legs temporarily weaken as you conduct your own experiments on me."

"I've never been with a man!" John cried._ Bloody hell, did I just say that out loud?_ He forced himself to take a deep breath. "Sherlock, those things I said the other day - I mean, I've dated plenty of women, but I've never given a blow job before. I was just trying to . . . to rev you up a bit. I've never . . . _fuck_."

"I know." Sherlock smiled that insanely patronizing smile of his. "But you want to. I was watching closely before - you were just as affected as I was. You're aroused at the thought of performing fellacio on me. Of putting your fingers through my anal sphincter and trying to stroke my prostate. And I'm very, _very_ interested in it as well. I think I might like to try the reverse, too - I'm curious what your pre-ejaculate tastes like, and whether the skin on your neck tastes different from the skin over your stomach or the skin on your penis or the skin on your testicles. I think the next time you take a shower, I'm going to go lie on my bed and cup my own genitalia in my hands and think about what you look like when you're wet and naked." His fingers curled at his sides, as if he was trying to force himself to keep them there. "I'll leave my door open, so when you get out, you can see me lying there, my skin flushed from arousal and exertion and my eyes closed so I won't know until you come into my room whether you've decided to come touch me or not."

John was _very_ hard now. Frustratingly, achingly, hard, despite how Sherlock kept using the word "penis." And Sherlock was looking at him, waiting patiently for John to do something, but John didn't want to get up as long as he had that raging erection - surely Sherlock would see -

"It's all right, John," Sherlock said quietly. "I've gathered as much data as I need from you for the time being. You don't need to hide that you're aroused."

John groaned and levered himself off the couch. "I think I need a cold shower."

He realized the implications of his announcement - so close on the heels of Sherlock's - a moment too late. And there was no hiding the wave of lust that slammed through him at the sight of Sherlock's face in that moment.

"I'll leave the temperature up to you," Sherlock said softly. "But I'll be waiting in my room."


End file.
